Russia is putting extra security measures in place for its Victory Day parade in Moscow.
The annual celebration marks the Russian victory over Nazi Germany in the Second World War.
There are increased tensions raised by explosions and drone attacks, which Moscow is blaming on Ukraine.
It comes as president of the EU Commission Ursula von der Leyen arrived in Kyiv to mark the Europe Day celebration of peace and unity.
Ms von der Leyen travelled overnight on a train from Poland to meet with President Volodymyr Zelensky and discuss Ukraine's desire to join the European Union.
On Monday, air raid sirens sounded across Ukraine after the latest wave of Russian drone and missile strikes.
Moscow escalated attacks on the capital Kyiv and other cities ahead of Victory Day.
Ukraine says it destroyed all 35 Iranian-made drones which Russia launched overnight from Sunday into Monday.
Earlier this month, Ukraine launched a competition for drone developers to land an Unmanned Aerial Vehicle (UAV) on Red Square in Moscow during the 9 May parade for a cash prize.
The competition was announced by the co-founder of Monobank and developer of the Dovbush drone Volodymyr Yatsenko.